1. Field of the Invention
The present invention relates to a multi-chamber system of an etching facility for manufacturing semiconductor devices, and more particularly, to a multi-chamber system of an etching facility for manufacturing semiconductor devices which minimizes the space occupied by the facility by aligning a plurality of processing chambers with a transfer path in the center.
2. Background of the Related Art
The manufacturing of semiconductor devices involves many processes, including photolithography, etching, and thin film formation, which are repeatedly carried out during the manufacturing process. Generally, the etching process is carried out in a “focus-type” multi-chamber system which is capable of processing various process steps for wafers at the same time.
In particular, the multi-chamber system for a dry-etching process using plasma is operated with a plurality of processing chambers in which a high-vacuum state environment for the generation of plasma is formed. The system includes an inner transfer device for transporting wafers from a central chamber under a low vacuum state to the plurality of high vacuum processing chambers.
FIG. 1 illustrates a conventional focus-type multi-chamber system for a dry-etching process using plasma, which is constructed in such a manner that a hexagonal pillar-shaped central chamber 16 is located in its center; four processing chambers 15 are connected to four sides of the central chamber 16, and between the central chamber 16 and each of the processing chambers 15, there is formed a gate (not shown) for allowing the selective passage of wafers. An inner transfer device 14 inside the central chamber 16 is able to selectively load and unload the wafers into each processing chamber 15 through the gate. Note that the central chamber 16 can be formed as a square, pentagon, hexagon shape, etc., and FIG. 1 shows the normal hexagonal shape of the central chamber 16. Further, there is provided a vacuum pressure generator (not shown) in each of the processing chambers 15 and the central chamber 16.
Therefore, the inner transfer device 14 transports wafers to the processing chamber 15 under the vacuum pressure environment. In addition to the central chamber 16, a load lock chamber 13, serving as a stand-by area for the wafers under a low vacuum state, is located between the central chamber 16 and the wafers which are under atmospheric pressure in cassettes 11.
The load lock chamber 13 comprises an input load lock chamber for stacking wafers before processing, and an output load lock chamber for stacking wafers after processing.
In addition to the two load lock chambers 13, there is connected a cassette stage 12 having the cassettes 11 mounted thereon for easy transportation of wafers under atmospheric pressure.
Therefore, in the conventional multi-chamber system, if the cassette 11 is mounted on the cassette stage 12, an operator or the automatic transfer mechanism, etc., inside the load lock chamber 13 transfers the cassette 11 having wafers thereon to the load lock chamber 13, and then, the load lock chamber 13 is sealed and placed under a low vacuum state. When the load lock chamber 13 reaches a certain level of vacuum, the gate of the load lock chamber 13 is opened, an inner transfer device 14 inside the central chamber 16 mounts wafers individually or in groups on a transfer arm (not shown) under a low vacuum state, and transfers them to a specific processing chamber 15 by rotating horizontally a certain angle, and proceeding toward the specific processing chamber 15.
In addition, after wafers are transported into the processing chamber 15, the gate of the processing chamber 15 is shut, and a specific corresponding process is carried out. The processed wafers are removed from the processing chamber by the inner transfer device 14 of the central chamber 16, and stacked on the cassette 11 inside the load lock chamber 13.
Here, while a specific process is carried out inside a specific processing chamber 15, the inner transfer device 14 is capable of continuously loading and unloading wafers to another processing chamber 15. Therefore, a plurality of wafers can be processed inside a plurality of processing chambers 15 at the same time.
However, the conventional multi-chamber system, which is constructed as described above, i.e., the hexagonal pillar shaped central chamber 16, four processing chambers 15 and two load lock chambers 13 surrounding the central chamber 16, occupies a space of width “W” inside the fabrication line layout, requiring a large vacuum facility to maintain the central chamber 16 in a vacuum state and increasing the expenses for the facilities and their installation.
In addition, the space taken up by the central chamber increases with the number of processing chambers. For instance, six processing chambers and two load lock chambers require an octagonal pillar shaped central chamber which takes up more space than the hexagonal pillar-shaped central chamber shown in FIG. 1.
Therefore, if the number of processing chambers is increased, a different multi-chamber system is necessary, occupying additional cleanroom space and requiring additional expense. Various process gases and vacuum-related apparatus connected to the processing chamber or the load lock chamber must also be installed in duplicate.
An attempt to increase the number of processing chambers of the focus-type multi-chamber system, as shown in FIG. 2, comprises two central chambers 16, each connected to three processing chambers 15. The two central chambers 16 are connected to each other by a connection load lock chamber 17 between them. Two of the conventional focus-type multi-chamber systems 10 are thereby connected.
However, the installation of the six processing chambers 15 and one connection load lock chamber 17 as shown in FIG. 2 costs more than the installation of an additional focus-type multi-chamber system 10 as shown in FIG. 1, and the seven-chamber set-up still occupies a lot of space in the cleanroom, and requires duplicate installation of various processing gases and vacuum-related apparatus.
Furthermore, as shown in FIG. 3, the conventional focus-type multi-chamber system 10 is normally installed inside the cleanroom along with other facilities 20, with the cassette stages on the other facilities all being disposed to one side. Therefore, it is necessary for an operator or an automatic cassette car to transport cassettes between facilities.
In addition to the disadvantages of the focus-type multi-chamber system, the inner transfer device moves wafers under a vacuum state, and therefore, the wafers cannot be attached by vacuum-absorption, and are simply gravity-supported by the transfer arm. The wafers must therefore be moved at a low speed so as not to be displaced from the transfer arm, which results in a very slow wafer transfer operation.